Dual and Specific Inhibition of NAMPT and PAK4 By KPT-9274 Decreases Kidney Cancer Growth

Kidney cancer (or renal cell carcinoma, RCC) is the sixth most common malignancy in the United States and one of the relatively few whose incidence is increasing. Because of the near universal resistance which occurs with the use of current treatment regimens, reprogrammed metabolic pathways are being investigated as potential targets for novel therapies of this disease. Borrowing from studies on other malignancies, we have identified the PAK4 and NAD biosynthetic pathways as being essential for RCC growth. We now show, using the dual PAK4/NAMPT inhibitor KPT-9274, that interference with these signaling pathways results in reduction of G2-M transit as well as induction of apoptosis and decrease in cell invasion and migration in several human RCC cell lines. Mechanistic studies demonstrate that inhibition of the PAK4 pathway by KPT-9274 attenuates nuclear β-catenin as well as the Wnt/β-catenin targets cyclin D1 and c-Myc. Furthermore, NAPRT1 downregulation, which we show occurs in all RCC cell lines tested, makes this tumor highly dependent on NAMPT for its NAD requirements, such that inhibition of NAMPT by KPT-9274 leads to decreased survival of these rapidly proliferating cells. When KPT-9274 was administered in vivo to a 786-O (VHL-mut) human RCC xenograft model, there was dose-dependent inhibition of tumor growth with no apparent toxicity; KPT-9274 demonstrated the expected on-target effects in this mouse model. KPT-9274 is being evaluated in a phase I human clinical trial in solid tumors and lymphomas, which will allow this data to be rapidly translated into the clinic for the treatment of RCC. Mol Cancer Ther; 15(9); 2119-29. ©2016 AACR.

The Nephrologist's Tumor: Basic Biology and Management of Renal Cell Carcinoma

Kidney cancer, or renal cell carcinoma (RCC), is a disease of increasing incidence that is commonly seen in the general practice of nephrology. However, RCC is under-recognized by the nephrology community, such that its presence in curricula and research by this group is lacking. In the most common form of RCC, clear cell renal cell carcinoma (ccRCC), inactivation of the von Hippel-Lindau tumor suppressor is nearly universal; thus, the biology of ccRCC is characterized by activation of hypoxia-relevant pathways that lead to the associated paraneoplastic syndromes. Therefore, RCC is labeled the internist's tumor. In light of this characterization and multiple other metabolic abnormalities recently associated with ccRCC, it can now be viewed as a metabolic disease. In this review, we discuss the basic biology, pathology, and approaches for treatment of RCC. It is important to distinguish between kidney confinement and distant spread of RCC, because this difference affects diagnostic and therapeutic approaches and patient survival, and it is important to recognize the key interplay between RCC, RCC therapy, and CKD. Better understanding of all aspects of this disease will lead to optimal patient care and more recognition of an increasingly prevalent nephrologic disease, which we now appropriately label the nephrologist's tumor.

Abstract 3799: The PAK4 allosteric modulator (KPT-9274) attenuates the growth of renal cell carcinoma

Renal cell carcinoma (RCC) is an increasingly prevalent cancer type that is frequently asymptomatic on presentation and is associated with poor responses and resistance even to the current targeted therapies. Thus, novel therapeutic approaches to treat this disease are urgently needed. P21-activated kinase 4 (PAK4) is a mediator of filopodia formation and stabilizes β-catenin transcriptional activity, both of which are integral to nephrogenesis and cancer. We hypothesized that inhibitors of the PAK4 signaling pathway would result in salutary effects on RCC. To test this, we evaluated the in vitro response of several human RCC cells and normal kidney proximal epithelial cells (NHKs) to the specific PAK4 Allosteric Modulators (PAMs; KPT-8752 and KPT-9274). 786-O (VHL-mutant RCC) and caki-1 (VHL-wt RCC) cells showed decreases in cell viability (MTT), induction of apoptosis and arrest in G2/M phase when incubated with these inhibitors. These responses were diminished in NHK cells which served as a “normal” control cell line. Target and specific pathway proteins (phospho-PAK4, Phospho-β-catenin, c-Myc and cyclin D1) were reduced after RCC, but not NHK, were incubated with KPT-8752 and KPT-9274. To confirm specificity of the inhibitor to PAK4, all these responses were reproduced in RCC cells using specific PAK4 siRNA. Since ∼85% of RCC cases are associated with mutation in vhl we used 786-0 xenograft mouse model to evaluate the clinical candidate KPT-9274. KPT-9274 was orally administered at 100 and 200 mg/kg BIDX5 for 4 weeks, resulting in clear attenuation of tumor growth at both doses. There was no obvious change in the health or weight of any of the animals when compared to vehicle group suggesting manageable tolerability. We are currently evaluating combination therapy and plan to test this inhibitor on a metastatic RCC model. In summary, PAK4 inhibitors show considerable promise as novel treatments of RCC as a single agent and warrants further investigation.

Citation Format: Robert H. Weiss, Omran Abu Aboud, Erkan Baloglu, William Senapedis, Sharon Shacham. The PAK4 allosteric modulator (KPT-9274) attenuates the growth of renal cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3799.

Abstract LB-086: Combination therapy of immune checkpoint and nuclear exporter inhibitors in a renal cell carcinoma mouse model

Selective inhibitor of nuclear export (SINE) compounds represent a novel class of drugs that have shown therapeutic equivalence to multiple kinase inhibitors in pre-clinical studies of renal cell carcinoma (RCC) and are currently in phase I/II clinical trials for patients with advanced malignancies including RCC. Immune checkpoint blockade using antibodies against PD-1 or PD-L1 has also shown promising results in phase I/II/III clinical trials for RCC, with objective tumor responses of around 20% that rise to 40-50% with the combination of antibodies against CTLA-4. Here, we tested the hypothesis that the oral SINE compound, selinexor (KPT-330), would induce rapid death of RCC tumor cells and prime the tumor microenvironment for a response to checkpoint inhibition with antibodies against PD-1 or CTLA-4. Groups of 10, six-week old, male, syngeneic (Balb/c) mice were injected heterotopically (subcutaneous) with 500,000 RENCA cells. After visible tumors appeared seven days later, mice were treated every three days with vehicle (controls), selinexor, anti-PD-1, or anti-CTLA4 alone, or with selinexor in combination with either antibody. Mice were euthanized 10 days after the initiation of treatment when the control groups reached the tumor endpoint. Tumor volume, tumor size, and tumor growth rate were determined by physical measurements; the composition of the tumor immune environment was determined by multi-parameter flow cytometry. As expected, selinexor significantly reduced the overall tumor burden (P<0.05) and the checkpoint inhibitors had only modest effects on tumor growth in this acute 10-day treatment setting, both when used alone alone or in combination with selinexor. Consistent with the hypothesis, selinexor altered the local immune environment, increasing the relative number of T cells and NKT cells with a concomitant reduction in Gr1+ and CD11b+ myeloid cells, and Foxp3+ regulatory T cells (Tregs). Anti-CTLA4 and anti-PD-1 alone led to comparable increases in the relative number of T cells and NKT cells, but with an additional increase in the proportion of effector and activated T cells. The combination of selinexor with either checkpoint blockade antibody resulted in similar reorganization of the tumor immune landscape, with increases in the total number of T cells, effector and activated T cells, and NKT cells and reductions in myeloid cells and Tregs. The data suggest that treatment with selinexor promotes a rapid reduction in tumor burden, while priming the inflammatory and immune environment to potentially maximize the therapeutic effects of checkpoint inhibition. Additional pre-clinical assessments of dose and schedule for this combination can and will be feasibly done in the RENCA model of RCC.

Citation Format: Josephine Trott, Katie Anderson, Jeffrey Kim, Ashley Graef, Sharon Shacham, Yosef Landesman, Aaron Sarver, Jaime Modiano, Robert H. Weiss. Combination therapy of immune checkpoint and nuclear exporter inhibitors in a renal cell carcinoma mouse model. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-086.

Addition of DHA Synergistically Enhances the Efficacy of Regorafenib for Kidney Cancer Therapy

Kidney cancer is the sixth most common cancer in the United States, and its incidence is increasing. The treatment of this malignancy took a major step forward with the recent introduction of targeted therapeutics, such as kinase inhibitors. Unfortunately, kinase inhibition is associated with the onset of resistance after 1 to 2 years of treatment. Regorafenib, like many multikinase inhibitors, was designed to block the activities of several key kinase pathways involved in oncogenesis (Ras/Raf/MEK/ERK) and tumor angiogenesis (VEGF-receptors), and we have recently shown that it also possesses soluble epoxide hydrolase (sEH) inhibitory activity, which may be contributing to its salutary effects in patients. Because sEH inhibition results in increases in the DHA-derived epoxydocosapentaenoic acids that we have previously described to possess anticancer properties, we asked whether the addition of DHA to a therapeutic regimen in the presence of regorafenib would enhance its beneficial effects in vivo We now show that the combination of regorafenib and DHA results in a synergistic effect upon tumor invasiveness as well as p-VEGFR attenuation. In addition, this combination showed a reduction in tumor weights, greater than each agent alone, in a mouse xenograft model of human renal cell carcinoma (RCC), yielding the expected oxylipin profiles; these data were supported in several RCC cell lines that showed similar results in vitro Because DHA is the predominant component of fish oil, our data suggest that this nontoxic dietary supplement could be administered with regorafenib during therapy for advanced RCC and could be the basis of a clinical trial. Mol Cancer Ther; 15(5); 890-8. ©2016 AACR.

Changes in PTGS1 and ALOX12 Gene Expression in Peripheral Blood Mononuclear Cells Are Associated with Changes in Arachidonic Acid, Oxylipins, and Oxylipin/Fatty Acid Ratios in Response to Omega-3 Fatty Acid Supplementation

Introduction

There is a high degree of inter-individual variability among people in response to intervention with omega-3 fatty acids (FA), which may partly explain conflicting results on the effectiveness of omega-3 FA for the treatment and prevention of chronic inflammatory diseases. In this study we sought to evaluate whether part of this inter-individual variability in response is related to the regulation of key oxylipin metabolic genes in circulating peripheral blood mononuclear cells (PBMCs).

Methods

Plasma FA and oxylipin profiles from 12 healthy individuals were compared to PBMC gene expression profiles following six weeks of supplementation with fish oil, which delivered 1.9 g/d eicosapentaenoic acid (EPA) and 1.5 g/d docosahexaenoic acid (DHA). Fold changes in gene expression were measured by a quantitative polymerase chain reaction (qPCR).

Results

Healthy individuals supplemented with omega-3 FA had differential responses in prostaglandin-endoperoxide synthase 1 (PTGS1), prostaglandin-endoperoxide synthase 2 (PTGS2), arachidonate 12-lipoxygenase (ALOX12), and interleukin 8 (IL-8) gene expression in isolated PBMCs. In those individuals for whom plasma arachidonic acid (ARA) in the phosphatidylethanolamine (PE) lipid class decreased in response to omega-3 intervention, there was a corresponding decrease in gene expression for PTGS1 and ALOX12. Several oxylipin product/FA precursor ratios (e.g. prostaglandin E₂ (PGE₂)/ARA for PTGS1 and 12-hydroxyeicosatetraenoic acid (12-HETE)/ARA for ALOX12) were also associated with fold change in gene expression, suggesting an association between enzyme activity and gene expression. The fold-change in PTGS1 gene expression was highly positively correlated with ALOX12 gene expression but not with PTGS2, whereas IL-8 and PTGS2 were positively correlated.

Conclusions

The regulation of important oxylipin metabolic genes in PBMCs varied with the extent of change in ARA concentrations in the case of PTGS1 and ALOX12 regulation. PBMC gene expression changes in response to omega-3 supplementation varied among healthy individuals, and were associated with changes in plasma FA and oxylipin composition to different degrees in different individuals.

Trial Registration

clinicaltrials.gov NCT01838239

Abstract 2644: Inhibition of PAK4 attenuates renal cell carcinoma (RCC) growth

Renal cell carcinoma (RCC) is an increasingly prevalent cancer type that is frequently asymptomatic on presentation and is associated with poor responses and resistance even to the current targeted therapies. Thus, novel therapeutic approaches to treat this disease are urgently needed. P21-activated kinase 4 (PAK4) is a mediator of filopodia formation and stabilizes β-catenin transcriptional activity. PAK4 lies in a pathway integral to both nephrogenesis and cancer. We hypothesized that inhibitors of the PAK4 signaling pathway would result in salutary effects on RCC. To test this, we evaluated the in vitro response of RCC cells to the specific PAK4 Allosteric Modulators (PAMs; KPT-8752 and KPT-9274). Similar to cells of other cancer types, 786-O (VHL-mutant RCC) showed decreases of both Phospho-PAK4 and Phospho-β-catenin after 24 h of incubation with 10 μM KPT-8752. In addition, both 786-O and ACHN (VHL-wildtype RCC cells) showed a marked time-dependent decrease in cell viability from 24 to 72 h of incubation from 2 to 10 μM of KPT-8752. KPT-9274 was orally administered at 25 and 100 mg/kg twice a day for 5 days/week to Caki-1 (VHL-wildtype RCC) and 786-O subcutaneous nude mouse xenograft models. In these studies the tumor growth rate was attenuated at both doses in the 786-O cells and at the higher dose for Caki-1 cells. There was no obvious change in the health of any of the animals suggesting manageable tolerability. We are currently evaluating combination therapy in our laboratory. In summary, PAK4 inhibitors show considerable promise as novel treatments of RCC as a single agent and warrant further investigation.

Citation Format: Omran Abu Aboud, William Senapedis, Yosef Landesman, Erkan Baloglu, Robert H. Weiss. Inhibition of PAK4 attenuates renal cell carcinoma (RCC) growth. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2644. doi:10.1158/1538-7445.AM2015-2644

The cpk model of recessive PKD shows glutamine dependence associated with the production of the oncometabolite 2-hydroxyglutarate

Since polycystic kidney disease (PKD) was first noted over 30 years ago to have neoplastic parallels, there has been a resurgent interest in elucidating neoplasia-relevant pathways in PKD. Taking a nontargeted metabolomics approach in the B6(Cg)-Cys1(cpk/)J (cpk) mouse model of recessive PKD, we have now characterized metabolic reprogramming in these tissues, leading to a glutamine-dependent TCA cycle shunt toward total 2-hydroxyglutarate (2-HG) production in cpk compared with B6 wild-type kidney tissue. After confirmation of increased 2-HG expression in immortalized collecting duct cpk cells as well as in human autosomal recessive PKD tissue using targeted analysis, we show that the increase in 2-HG is likely due to glutamine-sourced α-ketoglutarate. In addition, cpk cells require exogenous glutamine for growth such that inhibition of glutaminase-1 decreases cell viability as well as proliferation. This study is a demonstration of the striking parallels between recessive PKD and cancer metabolism. Our data, once confirmed in other PKD models, suggest that future therapeutic approaches targeting this pathway, such as using glutaminase inhibitors, have the potential to open novel treatment options for renal cystic disease.

Spontaneous γH2AX Foci in Human Solid Tumor-Derived Cell Lines in Relation to p21WAF1 and WIP1 Expression

Phosphorylation of H2AX on Ser139 (γH2AX) after exposure to ionizing radiation produces nuclear foci that are detectable by immunofluorescence microscopy. These so-called γH2AX foci have been adopted as quantitative markers for DNA double-strand breaks. High numbers of spontaneous γH2AX foci have also been reported for some human solid tumor-derived cell lines, but the molecular mechanism(s) for this response remains elusive. Here we show that cancer cells (e.g., HCT116; MCF7) that constitutively express detectable levels of p21^WAF1 (p21) exhibit low numbers of γH2AX foci (<3/nucleus), whereas p21 knockout cells (HCT116p21−/−) and constitutively low p21-expressing cells (e.g., MDA-MB-231) exhibit high numbers of foci (e.g., >50/nucleus), and that these foci are not associated with apoptosis. The majority (>95%) of cells within HCT116p21−/− and MDA-MB-231 cultures contain high levels of phosphorylated p53, which is localized in the nucleus. We further show an inverse relationship between γH2AX foci and nuclear accumulation of WIP1, an oncogenic phosphatase. Our studies suggest that: (i) p21 deficiency might provide a selective pressure for the emergence of apoptosis-resistant progeny exhibiting genomic instability, manifested as spontaneous γH2AX foci coupled with phosphorylation and nuclear accumulation of p53; and (ii) p21 might contribute to positive regulation of WIP1, resulting in dephosphorylation of γH2AX.

Grade-Dependent Metabolic Reprogramming in Kidney Cancer Revealed by Combined Proteomics and Metabolomics Analysis

Kidney cancer [or renal cell carcinoma (RCC)] is known as "the internist's tumor" because it has protean systemic manifestations, suggesting that it utilizes complex, nonphysiologic metabolic pathways. Given the increasing incidence of this cancer and its lack of effective therapeutic targets, we undertook an extensive analysis of human RCC tissue employing combined grade-dependent proteomics and metabolomics analysis to determine how metabolic reprogramming occurring in this disease allows it to escape available therapeutic approaches. After validation experiments in RCC cell lines that were wild-type or mutant for the Von Hippel-Lindau tumor suppressor, in characterizing higher-grade tumors, we found that the Warburg effect is relatively more prominent at the expense of the tricarboxylic acid cycle and oxidative metabolism in general. Further, we found that the glutamine metabolism pathway acts to inhibit reactive oxygen species, as evidenced by an upregulated glutathione pathway, whereas the β-oxidation pathway is inhibited, leading to increased fatty acylcarnitines. In support of findings from previous urine metabolomics analyses, we also documented tryptophan catabolism associated with immune suppression, which was highly represented in RCC compared with other metabolic pathways. Together, our results offer a rationale to evaluate novel antimetabolic treatment strategies being developed in other disease settings as therapeutic strategies in RCC.

PPARα inhibition modulates multiple reprogrammed metabolic pathways in kidney cancer and attenuates tumor growth

Kidney cancer [renal cell carcinoma (RCC)] is the sixth-most-common cancer in the United States, and its incidence is increasing. The current progression-free survival for patients with advanced RCC rarely extends beyond 1-2 yr due to the development of therapeutic resistance. We previously identified peroxisome proliferator-activating receptor-α (PPARα) as a potential therapeutic target for this disease and showed that a specific PPARα antagonist, GW6471, induced apoptosis and cell cycle arrest at G0/G1 in RCC cell lines associated with attenuation of cell cycle regulatory proteins. We now extend that work and show that PPARα inhibition attenuates components of RCC metabolic reprogramming, capitalizing on the Warburg effect. The specific PPARα inhibitor GW6471, as well as a siRNA specific to PPARα, attenuates the enhanced fatty acid oxidation and oxidative phosphorylation associated with glycolysis inhibition, and PPARα antagonism also blocks the enhanced glycolysis that has been observed in RCC cells; this effect did not occur in normal human kidney epithelial cells. Such cell type-specific inhibition of glycolysis corresponds with changes in protein levels of the oncogene c-Myc and has promising clinical implications. Furthermore, we show that treatment with GW6471 results in RCC tumor growth attenuation in a xenograft mouse model, with minimal obvious toxicity, a finding associated with the expected on-target effects on c-Myc. These studies demonstrate that several pivotal cancer-relevant metabolic pathways are inhibited by PPARα antagonism. Our data support the concept that targeting PPARα, with or without concurrent inhibition of glycolysis, is a potential novel and effective therapeutic approach for RCC that targets metabolic reprogramming in this tumor.

Specific inhibition of the nuclear exporter exportin-1 attenuates kidney cancer growth

PURPOSE

Despite the advent of FDA-approved therapeutics to a limited number of available targets (kinases and mTOR), PFS of kidney cancer (RCC) has been extended only one to two years due to the development of drug resistance. Here, we evaluate a novel therapeutic for RCC which targets the exportin-1 (XPO1) inhibitor.

MATERIALS AND METHODS

RCC cells were treated with the orally available XPO1 inhibitor, KPT-330, and cell viability and Annexin V (apoptosis) assays, and cell cycle analyses were performed to evaluate the efficacy of KPT-330 in two RCC cell lines. Immunoblotting and immunofluorescence analysis were performed to validate mechanisms of XPO1 inhibition. The efficacy and on-target effects of KPT-330 were further analyzed in vivo in RCC xenograft mice, and KPT-330-resistant cells were established to evaluate potential mechanisms of KPT-330 resistance.

RESULTS

KPT-330 attenuated RCC viability through growth inhibition and apoptosis induction both in vitro and in vivo, a process in which increased nuclear localization of p21 by XPO1 inhibition played a major role. In addition, KPT-330 resistant cells remained sensitive to the currently approved for RCC multi-kinase inhibitors (sunitinib, sorafenib) and mTOR inhibitors (everolimus, temsirolimus), suggesting that these targeted therapeutics would remain useful as second line therapeutics following KPT-330 treatment.

CONCLUSION

The orally-available XPO1 inhibitor, KPT-330, represents a novel target for RCC whose in vivo efficacy approaches that of sunitinib. In addition, cells resistant to KPT-330 retain their ability to respond to available RCC therapeutics suggesting a novel approach for treatment in KPT-330-naïve as well as -resistant RCC patients.

Biomarkers in IgA nephropathy

IgA nephropathy is the most common primary glomerulonephritis and presents with gross hematuria and upper respiratory infection, with slow progression to end-stage renal disease in up to 50% of affected patients. Kidney biopsies are the gold standard method of diagnosis and frequently are not performed as the majority of individuals are asymptomatic. Thus, there is a need to discover and validate prognostic and predictive biomarkers that can be noninvasively obtained and are specific to this disease. Here we discuss the current state of research in this area and examine validated and clinically promising biofluid and tissue biomarkers of IgA nephropathy.

Novel inhibitors of nuclear transport cause cell cycle arrest and decrease cyst growth in ADPKD associated with decreased CDK4 levels

Autosomal-dominant polycystic kidney disease (ADPKD) is a progressive, proliferative renal disease. Kidneys from ADPKD patients are characterized by the presence of cysts that are marked by enhanced proliferation and apoptosis of renal tubular epithelial cells. Current treatment of this disease is supportive, as there are few if any clinically validated targeted therapeutics. Given the parallels between cystic disease and cancer, and in light of our findings of the efficacy of the nuclear transport inhibitors in kidney cancer, which has similarities to ADPKD, we asked whether such inhibitors show utility in ADPKD. In this study, we tested selective inhibitors of nuclear export (SINE) in two human ADPKD cell lines and in an in vivo mouse model of ADPKD. After effective downregulation of a nuclear exporter, exportin 1 (XPO1), with KPT-330, both cell lines showed dose-dependent inhibition of cell proliferation through G₀/G₁ arrest associated with downregulation of CDK4, with minimal apoptosis. To analyze mechanisms of CDK4 decrease by XPO1 inhibition, localization of various XPO1 target proteins was examined, and C/EBPβ was found to be localized in the nucleus by XPO1 inhibition, resulting in an increase of C/EBPα, which activates degradation of CDK4. Furthermore, inhibition of XPO1 with the parallel inhibitor KPT-335 attenuated cyst growth in vivo in the PKD1 mutant mouse model Pkd1(v/v). Thus, inhibition of nuclear export by KPT-330, which has shown no adverse effects in renal serum chemistries and urinalyses in animal models, and which is already in phase 1 trials for cancers, will be rapidly translatable to human ADPKD.

Novel sorafenib-based structural analogues: in-vitro anticancer evaluation of t-MTUCB and t-AUCMB

In the current work, we carried out a mechanistic study on the cytotoxicity of two compounds, trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-N-methyl-benzamide (t-AUCMB) and trans-N-methyl-4-{4-[3-(4-trifluoromethoxy-phenyl)-ureido]-cyclohexyloxy}-benzamide (t-MTUCB), that are structurally similar to sorafenib. These compounds show strong cytotoxic responses in various cancer cell lines, despite significant differences in the induction of apoptotic events such as caspase activation and lactate dehydrogenase release in hepatoma cells. Both compounds induce autophagosome formation and LC3I cleavage, but there was little observable effect on mTORC1 or the downstream targets, S6K1 and 4E-binding protein. In addition, there was an increase in the activity of upstream signaling through the IRS1/PI3K/Akt-signaling pathway, suggesting that, unlike sorafenib, both compounds induce mammalian target of rapamycin (mTOR)-independent autophagy. The autophagy observed correlates with mitochondrial membrane depolarization, apoptosis-inducing factor release, and oxidative stress-induced glutathione depletion. However, there were no observable changes in the endoplasmic reticulum-stress markers such as binding immunoglobulin protein, inositol-requiring enzyme-α, phosphorylated eukaryotic initiation factor 2, and the lipid peroxidation marker, 4-hydroxynonenal, suggesting endoplasmic reticulum-independent oxidative stress. Finally, these compounds do not have the multikinase inhibitory activity of sorafenib, which may be reflected in their difference in the ability to halt cell cycle progression compared with sorafenib. Our findings indicate that both compounds have anticancer effects comparable with sorafenib in multiple cell lines, but they induce significant differences in apoptotic responses and appear to induce mTOR-independent autophagy. t-AUCMB and t-MTUCB represent novel chemical probes that are capable of inducing mTOR-independent autophagy and apoptosis to differing degrees, and may thus be potential tools for further understanding the link between these two cellular stress responses.

On-chip detection of a single nucleotide polymorphism without polymerase amplification

A nanoparticle-assembled photonic crystal (PC) array was used to detect single nucleotide polymorphism (SNP). The assay platform with PC nanostructure enhanced the fluorescent signal from nanoparticle-hybridized DNA complexes due to phase matching of excitation and emission. Nanoparticles coupled with probe DNA were trapped into nanowells in an array by using an electrophoretic particle entrapment system. The PC/DNA assay platform was able to identify a 1 base pair (bp) difference in synthesized nucleotide sequences that mimicked the mutation seen in a feline model of human autosomal dominant polycystic kidney disease (PKD) with a sensitivity of 0.9 fg/mL (50 aM)-sensitivity, which corresponds to 30 oligos/array. The reliability of the PC/DNA assay platform to detect SNP in a real sample was demonstrated by using genomic DNA (gDNA) extracted from the urine and blood of two PKD^- wild type and three PKD positive cats. The standard curves for PKD positive (PKD⁺) and negative (PKD^-) DNA were created using two feline-urine samples. An additional three urine samples were analyzed in a similar fashion and showed satisfactory agreement with the standard curve, confirming the presence of the mutation in affected urine. The limit of detection (LOD) was 0.005 ng/mL which corresponds to 6 fg per array for gDNA in urine and blood. The PC system demonstrated the ability to detect a number of genome equivalents for the PKD SNP that was very similar to the results reported with real time polymerase chain reaction (PCR). The favorable comparison with quantitative PCR suggests that the PC technology may find application well beyond the detection of the PKD SNP, into areas where a simple, cheap and portable nucleic acid analysis is desirable.

Stability of miRNA in human urine supports its biomarker potential

AIM

miRNAs are showing utility as biomarkers in urologic disease, however, a rigorous evaluation of their stability in urine is lacking. Here, we evaluate the stability of miRNAs in urine under clinically relevant storage procedures.

MATERIALS & METHODS

Eight healthy individuals provided clean catch urine samples that were stored at room temperature or at 4°C for 5 days, or subjected to ten freeze-thaw cycles at -80°C. For each condition, two miRNAs, miR-16 and miR-21, were quantitated by quantitative real-time PCR.

RESULTS

All conditions demonstrated a surprising degree of stability of miRNAs in the urine: by the end of ten freeze-thaw cycles, 23-37% of the initial amount remained; over the 5-day period of storage at room temperature, 35% of the initial amount remained; and at 4°C, 42-56% of the initial amount remained. Both miRNAs also showed degradation at approximately the same rate.

CONCLUSION

miRNAs are relatively stable in urine under a variety of storage conditions, which supports their utility as urinary biomarkers.

Metabolomic profiling of tumor-bearing mice

Metabolomics is one of the newcomers among the "omics" techniques, perhaps also constituting the most relevant for the study of pathophysiological conditions. Metabolomics may indeed yield not only disease-specific biomarkers but also profound insights into the etiology and progression of a variety of human disorders. Various metabolomic approaches are currently available to study oncogenesis and tumor progression in vivo, in murine tumor models. Many of these models rely on the xenograft of human cancer cells into immunocompromised mice. Understanding how the metabolism of these cells evolves in vivo is critical to evaluate the actual pertinence of xenograft models to human pathology. Here, we discuss various tumor xenograft models and methods for their metabolomic profiling to provide a short guide to investigators interested in this field of research.

Inhibition of PPARα induces cell cycle arrest and apoptosis, and synergizes with glycolysis inhibition in kidney cancer cells

Renal cell carcinoma (RCC) is the sixth most common cancer in the US. While RCC is highly metastatic, there are few therapeutics options available for patients with metastatic RCC, and progression-free survival of patients even with the newest targeted therapeutics is only up to two years. Thus, novel therapeutic targets for this disease are desperately needed. Based on our previous metabolomics studies showing alteration of peroxisome proliferator-activated receptor α (PPARα) related events in both RCC patient and xenograft mice materials, this pathway was further examined in the current study in the setting of RCC. PPARα is a nuclear receptor protein that functions as a transcription factor for genes including those encoding enzymes involved in energy metabolism; while PPARα has been reported to regulate tumor growth in several cancers, it has not been evaluated in RCC. A specific PPARα antagonist, GW6471, induced both apoptosis and cell cycle arrest at G0/G1 in VHL(+) and VHL(-) RCC cell lines (786-O and Caki-1) associated with attenuation of the cell cycle regulatory proteins c-Myc, Cyclin D1, and CDK4; this data was confirmed as specific to PPARα antagonism by siRNA methods. Interestingly, when glycolysis was blocked by several methods, the cytotoxicity of GW6471 was synergistically increased, suggesting a switch to fatty acid oxidation from glycolysis and providing an entirely novel therapeutic approach for RCC.

CRM1 blockade by selective inhibitors of nuclear export attenuates kidney cancer growth

PURPOSE

Renal cell carcinoma often presents asymptomatically and patients are commonly diagnosed at the metastatic stage, when treatment options are limited and survival is poor. Since progression-free survival using current therapy for metastatic renal cell carcinoma is only 1 to 2 years and existing drugs are associated with a high resistance rate, new pharmacological targets are needed. We identified and evaluated the nuclear exporter protein CRM1 as a novel potential therapy for renal cell carcinoma.

MATERIALS AND METHODS

We tested the efficacy of the CRM1 inhibitors KPT-185 and 251 in several renal cell carcinoma cell lines and in a renal cell carcinoma xenograft model. Apoptosis and cell cycle arrest were quantified and localization of p53 family proteins was assessed using standard techniques.

RESULTS

KPT-185 attenuated CRM1 and showed increased cytotoxicity in renal cell carcinoma cells in vitro with evidence of increased apoptosis as well as cell cycle arrest. KPT-185 caused p53 and p21 to remain primarily in the nucleus in all renal cell carcinoma cell lines, suggesting that the mechanism of action of these compounds depends on tumor suppressor protein localization. Furthermore, when administered orally in a high grade renal cell carcinoma xenograft model, the bioavailable CRM1 inhibitor KPT-251 significantly inhibited tumor growth in vivo with the expected on target effects and no obvious toxicity.

CONCLUSIONS

The CRM1 inhibitor protein family is a novel therapeutic target for renal cell carcinoma that deserves further intensive investigation for this and other urological malignancies.

Abstract 3226: Validation of novel RCC targets discovered by global metabolomics

Of the omics sciences, metabolomics is one of the newer methodologies. In this technique, all of the small molecule substances produced during bodily processes are measured. This includes endogenous metabolites as well as small peptides, amino acids, and (usually) body flora and drug metabolites. Rather than being participators in these processes, as are genes and transcripts, the metabolites produced are sentinels of “what is actually happening” in an organism. The so-called “cancer metabolome” is loosely defined as the entire suite of relatively low molecular weight (∼&lt;1.5 kD) metabolites germane to cancer and includes their changes relative to a control non-cancerous group of subjects or tissues. Using a human Caki-1 xenograft subcapsular mouse model of RCC (Ca. Res., 2012), we have performed non-targeted metabolomics of tumor tissue, blood, and urine. By correlation of this data with non-targeted metabolomics analysis from RCC patient urine (Int. J. Ca., 2012), we have identified three novel therapeutic targets for RCC: peroxisome proliferator-activated receptor alpha (PPARα), carnitine palmitoyltransferase-1 (CPT-1), and the tryptophan metabolic enzyme indoleamine-2,3-dioxygenase (IDO). We have performed in vitro validation of these potential targets using specific inhibitors. Incubation of RCC cells with inhibitors of PPARα (GW6471 and MK886) and CPT-1 (etomoxir) yields dose-dependent decreases in viability and/or cell cycle progression using multiple and disparate human RCC cell lines. In the case of IDO, selected downstream tryptophan metabolites had no effect on RCC viability when added directly to RCC cells, yet when incubated with CD3/CD28 stimulated peripheral blood mononuclear cells (PBMC), these metabolites decreased PBMC proliferation, suggesting that tryptophan metabolites may indeed attenuate immune surveillance in RCC. Furthermore, addition of the IDO inhibitor 1-methyltryptophan (1-MT) to RCC/PBMC co-cultures showed an 1-MT dose-dependent increase in proliferation of PBMCs. In vivo validation of all of these potential targets is currently underway in our laboratory. In summary, in this study we have used global, non-targeted metabolomics analysis to identify and begin to validate novel therapeutic targets which decrease RCC cell viability and proliferation (PPARα and CPT-1 inhibitor) or potentially enhance immunosurveillance (the IDO inhibitor 1-MT). This work shows for the first time the tremendous power of metabolomics starting from urine analysis to discovery to validation of new targets for RCC therapy.

Citation Format: Robert H. Weiss, Hiromi Wettersten, Omran Abu Aboud, Christine Mall, Matthewe Tan, Danny Alexander. Validation of novel RCC targets discovered by global metabolomics. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3226. doi:10.1158/1538-7445.AM2013-3226

From bead to flask: Synthesis of a complex β-amido-amide for probe-development studies

A concise synthesis of benzimidazole-substituted β-amido-amide LLW62 is presented. The original synthesis of compounds related to LLW62 was developed on Rink resin as part of a “one-bead, one-compound” combinatorial approach for on-bead screening purposes. The current synthesis is carried out in solution and is amenable to scale-up for follow-up studies on LLW62 and investigations of related structures. The key step involves the use of a β-amino acid-forming three-component reaction (3CR), the scope of which defines its role in the synthetic strategy.

A novel p21 attenuator which is structurally related to sorafenib

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Applications of metabolomics for kidney disease research: from biomarkers to therapeutic targets

Metabolomics is one of the relative newcomers of the omics techniques and is likely the one most closely related to actual real-time disease pathophysiology. Hence, it has the power to yield not only specific biomarkers but also insight into the pathophysiology of disease. Despite this power, metabolomics as applied to kidney disease is still in its early adolescence and has not yet reached the mature stage of clinical application, i.e., specific biomarker and therapeutic target discovery. On the other hand, the insight gained from hints into what makes these diseases tick, as is evident from the metabolomics pathways which have been found to be altered in kidney cancer, are now beginning to bear fruit in leading to potential therapeutic targets. It is quite likely that, with greater numbers of clinical materials and with more investigators jumping into the field, metabolomics may well change the course of kidney disease research.